The new science of proteomics, which seeks to provide global descriptions of protein expression and post-translational modification patterns in normal and pathologic tissues, is founded on the extraordinary sensitivity and discriminating power of mass spectrometry for the study of complex assemblages of proteins. The methodology for mass spectrometric analysis of entire proteomes is undergoing rapid evolution. In particular, new instrumentation and procedures are emerging that circumvent the need to employ proteolytic digestion to break proteins into small fragments for the purpose of rendering them tractable to mass spectrometric analysis. The new techniques open significant opportunities for sampling components of the proteome that have hitherto received little attention, and for investigating details of tissue differentiation and function in health and disease. To take advantage of these developments, the Hartwell Center for Bioinformatics and Biotechnology, a core facility at St. Jude Children's Research Hospital, is seeking to expand its mass spectrometry capabilities. A state-of-the-art instrument that uses matrix-assisted laser desorption/ionization time- of-flight mass spectrometry will be deployed for multidimensional analysis of protein expression in undigested tissue samples, and for direct imaging of tissue sections to study patterns of tissue differentiation. The same instrumentation will enable imaging studies of lipid distribution and drug targeting previously unavailable at the institution. We have identified six major, NIH funded research programs under way at St. Jude Children's Research Hospital with immediate need for this technology. These programs cover a broad range of topics including Pharmaceutical Science, Molecular Pharmacology, Genetics and Tumor Cell Biology, and Developmental Neurobiology. There are many other programs that have similar needs, or will have in the near future. The instrument will be incorporated into the Hartwell Center for present and future needs in basic biomedical research. Relevance St. Jude Children's Research Hospital in Memphis is seeking to deploy a mass spectrometer with new capabilities for tissue imaging to study normal and pathologic tissue types. The instrument will provide information about the proteins responsible for functional specialization of different cell types, the distribution of the various lipids that form cell membranes, and the distribution of drugs that are administered for the treatment of cancers. [unreadable] [unreadable] [unreadable]